1. Field of the invention
The present invention relates to apparatus for the non-destructive inspection of parts by irradiation, for example using X or gamma radiation, which includes a sighting unit.
2. Summary of the prior art
Such apparatus essentially comprises a unit for emitting the radiation towards the part to be inspected, and means for taking an image of the part, such as a photographic film. In order to locate easily the direction of the radiation beam and to check that the image obtained does relate to the irradiated area of the part, the apparatus is frequently provided with a sighting unit comprising means for emitting a ray of light which is temporarily included in the radiation beam and which supplies a reference point for observation through its interference with the part. However, the problem with this is that the light ray emitter is cumbersome, and its presence impedes the transmission of the checking radiation.
It is necessary therefore to resort to removing the light ray emitter after the stage of setting the sighting on the area of the part to be checked, which is hardly possible if the apparatus has been inserted inside certain parts such as small diameter bores. Moreover, the light ray emitter can prevent the introduction of the apparatus into such bores.